I am brewing some brewferm triple in a coopers fernentor. The fermentor has no airlock, just the non-closed top. The fermentation started on Saturday.
Tonight I went out for dinner and when I was back realized that because of my son trying to open it, my wife put something on the top not allowing the carbone Dioxide for several hours to go out. What are the consecuences of this?Will it continue normally now?

The lid didnt blow off...what about the beer? Will the fermentation continue normally?

yes, it's not critical to have an airtight fermentation unless the fermentor is sitting in a super dusty, windy location where something could blow in. i have fermented without any lid at all (as was done for centuries) and the beer was fine.